1. Field of the Invention
The present invention relates to the field of electronics. More specifically, the present invention relates to a method and system for mounting oversized electrical components on a circuit board so that the assembly height is minimized and the assembly can conform to predefined physical limits.
2. Background of the Art
Common practice in the data processing, network infrastructure, and telecommunication industries is to combine computer systems into specially designed rooms known as data centers. Data Centers often contain one or more racks or chassis that are populated by various system components. These system components include among other things processor modules, power supplies, networking switches, and storage appliances such as hard drive arrays and tape backup systems. The overhead costs associated with these data centers are extremely high. The data centers often require highly trained personnel, power conditioners, and special security measures, environmental controls such as air conditioning and dehumidifiers, and high bandwidth internetworking connections. Therefore, there are financial incentives to increasing the total number of system components that can be installed into any given data center. The industry addresses this condition by maximizing the density of electronic equipment that can fit into each square foot of a data center.
The electronic equipment in a data center is arranged with each rack or chassis containing individual subsystems. The subsystems are commonly housed in a carrier. The carriers are installed into a chassis and mechanically and electrically connected to a backplane. A chassis may contain one to several carriers. Additionally, the carriers may contain an individual board that performs a specific function such as video input/output, Ethernet connection, fiber-optic communication and many other system functions. Within a carrier there are designated several module bays that are capable of housing an electronics board such as an Advanced Mezzanine Card (AMC). The bays are allocated a specific amount of carrier space as allowed by the industrial standards discussed below. A board that occupies one bay is commonly referred to as a half-height board. When a board contains components having dimensions which cannot be accommodated by a single module bay, the board may occupy two adjacent bays; this is referred to as a full-height board. The industry strives to use half-height boards when ever possible in order to optimize the electronic density of the data center.
Industry groups such as the Institute of Electrical and Electronics Engineers (IEEE), VMEBus International Trade Association (VITA), and the PCI Industrial Computer Manufacturing Group (PICMG) have defined various standards that facilitate interoperability between components from different manufacturers. These standards, IEEE 1014, and ANSI/VITA 1-1994 (R2002), and PICMG AMC.0 describe the electrical interface and mechanical form a subsystem must conform to for proper functionality with other subsystems that follow the same standard.
Typically, these standards describe a maximum height an electrical component is permitted to protrude from each side of a printed circuit board (PCB). For example, the PICMG AMC.0 specification defines the mechanical form factor for a half-height Advanced Mezzanine Card (AMC). This specification limits the maximum amount that an electrical component can protrude above Component Side 1 on an AMC to 8.18 mm and to 3.4 mm for the reverse Component Side 2. Some commonly available components such as most common modular jack connectors used in twisted pair Ethernet networking are too tall to use given this height limit and still conform to the specification for a half-height board. This narrows the pool of available components that can be mounted on a PCB and still meet the specification. The current solutions for this situation are to use two adjacent bays for a single AMC or deviate from common electrical components and use custom and proprietary designed electronic components. Both of these current solutions are very expensive and not favored in the industry. First, using two bays for a single board does not optimize the density of electronic devices in each square foot of a data center. Secondly, designing and manufacturing custom components is both expensive and time consuming; it is preferred to maximize the use of common or off-the-shelf components whenever possible.
One teaching which addresses the need for compact electrical component mounting is found in U.S. Pat. No. 5,702,271 the disclosure of which is hereby incorporated by reference. U.S. Pat. No. 5,702,271 teaches the use of a custom-designed modular jack in combination with a circuit board having an aperture which receives a lower portion of the jack housing, when the jack is mounted on the component surface of the circuit board. This approach enables the over-sized jack to be used without exceeding the height standard for the circuit board components. This approach, while useful, provides only a small amount of additional mounting height space and requires a custom component.
Efforts to provide a generally applicable mounting arrangement for standard components having an over-sized height dimension which exceeds the appropriate height standard have not met with success to date.